Porous Insert for Nozzle of an Injection Molding System

Abstract

A nozzle assembly for an injection molding system has a nozzle adapter with one or more vent holes therein. A porous metal insert is provided in fluid communication with at least one of the vent holes. The porous metal insert is also in fluid communication with a flow channel through the nozzle assembly. As molten polymeric material advances through the flow channel from a barrel to a mold assembly, gases entrained in the molten polymeric material are vented through the porous metal insert and escape through the one or more vent holes. Pressurized air may be introduced through the vent holes, such as by one or more blow-back modules, to unclog pores of the one or more porous metal inserts between shots of the injection molding system.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is the non-provisional, and claims the benefit of the filing date, of U.S. Provisional Application No. 62 / 303,016, filed Mar. 3, 2016, which is hereby incorporated herein by reference.FIELD OF THE INVENTION[0002]The present application relates generally to the venting of gases from molten polymeric resin from injection molding systems and, more particularly, to the use of a porous metal insert in a nozzle of an injection unit for an injection molding system.BACKGROUND OF THE INVENTION[0003]While there can be many contributing factors to defects in injection molded articles, trapped gases within a mold cavity is often at least a significant cause. Part quality shortcomings that can be attributed to trapped gases include short shots, inconsistent distribution of park weight, flash (particularly in thin-walled parts), sink, air bubbles, black spots, and warpage. Trapped gases entrained in molten resin can also ignite in the m...

AI Technical Summary

Benefits of technology

The present disclosure relates to an injection molding system that uses a porous metal insert in the nozzle, which allows for better control of resin temperature and viscosity, and prevents defects caused by trapped gases. The system also allows for more expedient venting by providing a venting location that is sufficient to prevent resin build-up and clogging of vent pores. The set screws facilitate replacement of the porous metal inserts in case of clogging.

Problems solved by technology

While there can be many contributing factors to defects in injection molded articles, trapped gases within a mold cavity is often at least a significant cause.

Trapped gases entrained in molten resin can also ignite in the mold cavity, causing charring to regions of the molded part.

However, these methodologies require costly modifications to existing molds or customization of molds during their initial manufacture so as to provide effective venting.

Since gas entrained in the molten resin displaces the molten resin, such entrained gas can result in the delivery of less actual molten resin than desired.

Images